fun getOAuthToken(scopes: Array<String>): FxaResult<OAuthInfo> (source)
Fetches a new access token for the desired scopes using an internally stored refresh token.
scopes - List of OAuth scopes for which the client wants access
FxaException.Unauthorized - if the token could not be retrieved (eg. expired refresh token)
Return
FxaResult<OAuthInfo> that stores the token, along with its scopes and keys when complete